Disclosed are chromene derivatives based on a chromene amide isolated from Amyris texana. Also disclosed are compositions containing chromene derivatives (synthetic or natural) based on a chromene amide isolated from Amyris texana. Furthermore there are provided methods for repelling blood-sucking and biting insects, ticks and mites involving treating (or exposing) an object (e.g., mammals such as humans) or area (e.g., a surface such as human skin) with a blood-sucking and biting insects, ticks and mites repelling effective amount of at least one compound selected from chromene derivatives (synthetic or natural) based on a chromene amide isolated from Amyris texana. 
Dengue fever and yellow fever are caused by arboviruses which are transmitted by female mosquitoes belonging to the genus Aedes, particularly Ae. aegypti. Symptoms of dengue infection in humans include headache, fever, exhaustion, severe muscle and joint pain, swollen glands (lymphadenopathy), and rash. Other symptoms include bleeding gums, severe pain behind the eyes, and red palms and soles. The more severe form of this viral illness is dengue viral hemorrhagic fever which includes headache, fever, rash, and evidence of hemorrhage in the body. This form of dengue fever is life threatening and can progress to dengue shock syndrome, the most severe stage of the illness (Dengue Hemorrhagic Fever: Diagnosis, Treatment, Prevention and Control, 2nd Ed., Geneva, World Health Organization, 1997, pages 1-83).
After an individual receives a mosquito bite where saliva is injected from an infected mosquito, the incubation period ranges from three to eight days before the signs and symptoms of dengue appear. The temperature of the body rises quickly, as high as 40° C. with low heart rate (bradycardia) and low blood pressure (hypotension). Although there is a vaccine for yellow fever, there is no specific treatment or vaccine for dengue. The only way to prevent dengue virus transmission is to prevent bites from the disease-carrying mosquitoes by eliminating them. Application of insecticide is one of the major control methods for this medically important insect pest. However, few new insecticides have been developed for mosquito control and recently the most popular repellent, DEET, was reported as a neurotoxin (Corbel, V., et al., BMC Biology, 7:47 (2009)). New mosquito repellents without this potential side effect are thus desired.
We have identified some natural product-derived compounds that have higher duration of repellent action and potency against insects such as mosquitoes than DEET.